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1. Polyethylene
Polyethylene is the most commonly used resin in co-extruded barrier multilayer laminated films. According to the different densities, polyethylene is divided into low-density polyethylene (LDPE, density 0.925g/cm or less), medium-density polyethylene (MDPE, density 0.925~0.940g/cm3) and high-density polyethylene (HDPE, density 0.940g/cm3 or more), and people often refer to the medium polyethylene together with the low-density polyethylene as low-density polyethylene. Polyethylene is divided into low-density polyethylene (LDPE, density 0.940g/cm3 or less) and high-density polyethylene (HDPE. Density 0.940g/ctn or more) two broad categories.
(1) the general characteristics of polyethylene film
(1) has good mechanical properties
Polyethylene film tensile strength are more than 10MPa, some grades up to 20MPa or more.
¢Ú has a wide range of operating temperatures
Polyethylene film has very good low temperature resistance, can be used in -40 ¡æ below the low humidity environment for long-term use, at the same time, polyethylene also has good heat resistance, even if the heat resistance of low-density polyethylene film, the long-term use of its temperature is above 60 ¡æ, heat-resistant high-density polyethylene film can withstand 121 ¡æ cooking and sterilisation process.
¢ÛWater resistance, moisture-proof performance
Water resistance, moisture-proof performance is excellent and has a certain degree of oxygen barrier, oil resistance.
¢Ü Good heat sealing performance
Polyethylene film generally has good heat sealing performance, can be convenient, inexpensive ordinary heat sealing process, the polyethylene film made of bags of products.
¢Ý Good chemical stability
Except for a few kinds of strong oxidising acids, polyethylene films are highly resistant to a variety of common acids, alkalis, salts and many chemicals.
¢ÞExcellent hygiene performance
Polyethylene resin itself is non-toxic, odourless and tasteless, with reliable hygienic performance, and can be used for food and medicine packaging. The main defect in the performance of polyethylene packaging film is the poor barrier to oxygen, carbon dioxide and other non-polar gases permeability, in the packaging of oxygen-insulated storage of goods (processed foods, etc.), it is necessary to use a composite film containing polyethylene film layer and barrier film layer.
(2) Polyethylene Performance Theory
¢Ù low-density polyethylene (LDPE) basic characteristics of the application of a wide range of temperatures (between -60 ~ 60 ¡æ); LDPE film has a good heat sealing performance, but in the presence of debris, LDPE film heat sealing is poor; LDPE film has a better brightness (light transmittance of up to 80% or higher, haze can be in about 5%); LDPE Thin strength is poor (tensile strength is generally only a dozen MPa, but low melt flow rate grades of polyethylene has a high tensile strength, up to 20 MPa or more.
¢ÚBasic Characteristics of High Density Polyethylene (HDPE)
Compared with low-density polyethylene, high-density polyethylene has the following characteristics: the use of a wider range of temperatures, it can be used for both frozen food packaging, but also can be used at higher temperatures, when the density is high enough, polyethylene film can even be subjected to boiling sterilization (121 ¡æ cooking treatment); has a high mechanical strength (tensile strength of up to more than two times the LDPE packaging film); has a Excellent moisture resistance and good oil resistance. High-density polyethylene is commonly used packaging film in the barrier to water vapour performance is one of the best varieties, its oil resistance is not as good as nylon and other barrier films, but in the polyethylene film is the best varieties. Rigidity is better, but the softness is poor; transparency is poor, significantly lower than LDPE packaging film.
¢Û Basic characteristics of linear low-density polyethylene (LLDPE)
Puncture resistance, high tear propagation strength, outstanding stress cracking resistance; heat sealing performance is significantly better than ordinary high-density polyethylene and low-density polyethylene, with good inclusions can be sealed and high heat sealing strength; the film's mechanical strength is higher, between ordinary high-density polyethylene and low-density polyethylene, close to the high-density polyethylene.
Nanjing Suminoe Precision Machinery Co., Ltd. has professional cast film production line, the company's main cast film manufacturing production line: TPU hot melt adhesive film production line, CPP/CPE cast film production line, EVA solar encapsulation adhesive film production line, PE sanitary breathable film production line, PVDF cast film production line, PP 3D film production line, medical blood purification film production line, multi-layer co-extruded barrier film production line, LLDPE winding film production line, LLDPE film production line, LLDPE film production line, LLDPE film production line, LLDPE film production line, LLDPE film production line. production line, LLDPE winding film production line and so on.
Translated with DeepL.com (free version)
Polyethylene is the most commonly used resin in co-extruded barrier multilayer laminated films. According to the different densities, polyethylene is divided into low-density polyethylene (LDPE, density 0.925g/cm or less), medium-density polyethylene (MDPE, density 0.925~0.940g/cm3) and high-density polyethylene (HDPE, density 0.940g/cm3 or more), and people often refer to the medium polyethylene together with the low-density polyethylene as low-density polyethylene. Polyethylene is divided into low-density polyethylene (LDPE, density 0.940g/cm3 or less) and high-density polyethylene (HDPE. Density 0.940g/ctn or more) two broad categories.
(1) the general characteristics of polyethylene film
(1) has good mechanical properties
Polyethylene film tensile strength are more than 10MPa, some grades up to 20MPa or more.
¢Ú has a wide range of operating temperatures
Polyethylene film has very good low temperature resistance, can be used in -40 ¡æ below the low humidity environment for long-term use, at the same time, polyethylene also has good heat resistance, even if the heat resistance of low-density polyethylene film, the long-term use of its temperature is above 60 ¡æ, heat-resistant high-density polyethylene film can withstand 121 ¡æ cooking and sterilisation process.
¢ÛWater resistance, moisture-proof performance
Water resistance, moisture-proof performance is excellent and has a certain degree of oxygen barrier, oil resistance.
¢Ü Good heat sealing performance
Polyethylene film generally has good heat sealing performance, can be convenient, inexpensive ordinary heat sealing process, the polyethylene film made of bags of products.
¢Ý Good chemical stability
Except for a few kinds of strong oxidising acids, polyethylene films are highly resistant to a variety of common acids, alkalis, salts and many chemicals.
¢ÞExcellent hygiene performance
Polyethylene resin itself is non-toxic, odourless and tasteless, with reliable hygienic performance, and can be used for food and medicine packaging. The main defect in the performance of polyethylene packaging film is the poor barrier to oxygen, carbon dioxide and other non-polar gases permeability, in the packaging of oxygen-insulated storage of goods (processed foods, etc.), it is necessary to use a composite film containing polyethylene film layer and barrier film layer.
(2) Polyethylene Performance Theory
¢Ù low-density polyethylene (LDPE) basic characteristics of the application of a wide range of temperatures (between -60 ~ 60 ¡æ); LDPE film has a good heat sealing performance, but in the presence of debris, LDPE film heat sealing is poor; LDPE film has a better brightness (light transmittance of up to 80% or higher, haze can be in about 5%); LDPE Thin strength is poor (tensile strength is generally only a dozen MPa, but low melt flow rate grades of polyethylene has a high tensile strength, up to 20 MPa or more.
¢ÚBasic Characteristics of High Density Polyethylene (HDPE)
Compared with low-density polyethylene, high-density polyethylene has the following characteristics: the use of a wider range of temperatures, it can be used for both frozen food packaging, but also can be used at higher temperatures, when the density is high enough, polyethylene film can even be subjected to boiling sterilization (121 ¡æ cooking treatment); has a high mechanical strength (tensile strength of up to more than two times the LDPE packaging film); has a Excellent moisture resistance and good oil resistance. High-density polyethylene is commonly used packaging film in the barrier to water vapour performance is one of the best varieties, its oil resistance is not as good as nylon and other barrier films, but in the polyethylene film is the best varieties. Rigidity is better, but the softness is poor; transparency is poor, significantly lower than LDPE packaging film.
¢Û Basic characteristics of linear low-density polyethylene (LLDPE)
Puncture resistance, high tear propagation strength, outstanding stress cracking resistance; heat sealing performance is significantly better than ordinary high-density polyethylene and low-density polyethylene, with good inclusions can be sealed and high heat sealing strength; the film's mechanical strength is higher, between ordinary high-density polyethylene and low-density polyethylene, close to the high-density polyethylene.
Nanjing Suminoe Precision Machinery Co., Ltd. has professional cast film production line, the company's main cast film manufacturing production line: TPU hot melt adhesive film production line, CPP/CPE cast film production line, EVA solar encapsulation adhesive film production line, PE sanitary breathable film production line, PVDF cast film production line, PP 3D film production line, medical blood purification film production line, multi-layer co-extruded barrier film production line, LLDPE winding film production line, LLDPE film production line, LLDPE film production line, LLDPE film production line, LLDPE film production line, LLDPE film production line. production line, LLDPE winding film production line and so on.
Translated with DeepL.com (free version)